title: Development of a stable isotope dilution assay for tenuazonic acid.
abstract: A stable isotope dilution assay (SIDA) for the Alternaria mycotoxin tenuazonic acid was developed. Therefore, [(13)C(6),(15)N]-tenuazonic acid was synthesized from [(13)C(6),(15)N]-isoleucine by Dieckmann intramolecular cyclization after acetoacetylation with diketene. The synthesized [(13)C(6),(15)N]-tenuazonic acid was used as the internal standard for determination of tenuazonic acid in tomato products by liquid chromatography tandem mass spectrometry after derivatization with 2,4-dinitrophenylhydrazine. Method validation revealed a limit of detection of 0.1 μg/kg and a limit of quantitation of 0.3 μg/kg. Recovery was close to 100% in the range of 3-300 μg/kg. Determination of tenuazonic acid in two samples of different tomato ketchups (naturally contaminated) was achieved with a coefficient of variation of 2.3% and 4.7%. Different tomato products (n = 16) were analyzed for their content of tenuazonic acid using the developed SIDA. Values were between 15 and 195 μg/kg (tomato ketchup, n = 9), 363 and 909 μg/kg (tomato paste, n = 2), and 8 and 247 μg/kg (pureed tomatoes and comparable products, n = 5).
authors.affiliation: Technische Universität München, Lehrstuhl für Analytische Lebensmittelchemie, Alte Akademie 10, D-85354 Freising, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Asam
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Katharina
authors.initials: K
authors.lastname: Konitzer
authors.forename: Michael
authors.initials: M
authors.lastname: Rychlik
mesh_terms: D000528:Alternaria / Q000187:drug effects; D002247:Carbon Isotopes; D005506:Food Contamination / Q000032:analysis*; D005638:Fruit / Q000737:chemistry; D005659:Fungicides, Industrial / Q000032:analysis*; D007201:Indicator Dilution Techniques; D007553:Isotope Labeling; D018551:Solanum lycopersicum / Q000737:chemistry*; D009587:Nitrogen Isotopes; D013720:Tenuazonic Acid / Q000032:analysis*
chemical_list: D002247:Carbon Isotopes; D005659:Fungicides, Industrial; D009587:Nitrogen Isotopes; D013720:Tenuazonic Acid